Potential indicating device



June 13, 1961 1. ROSINEK 2,938,700

POTENTIAL INDICATING DEVICE Filed May 20, 1954 4 Sheets-Sheet 1 ATTORNEY4 Sheets-Sheet 5 BATTEKIE$ l l /0Z L l. ROSINEK POTENTIAL INDICATINGDEVICE hrk l5. 7

June 13, 1961 Filed May 20, 1954 INVENTOR ISIDORE ROSINEK BY 4 2wATTORNEY I States Patent C) 2,988,700 POTENTIAL INDICATING DEVICEIsidore Rosinek, 1520 E. 2nd St., Brooklyn 30, N .Y. Filed May 20, 1954,Ser. No. 431,215 7 Claims. (Cl. 324-122) This invention relates todevices for indicating the presence of a wide range of potentials, from80 volts to infinity and has for an object the provision of such :adevice which is safe and reliable, and which consists mainly of anactuating device and an indicator, or a combinational actuating deviceand indicator.

Another object. of the invention is the use of a cold cathode triggertube as the actuating device in a high potential indicating device.

Yet another object of the invention is the provision, in a highpotential indicating device, of a cold cathode trigger tube incombination with a circuit including nonlinear safety resistance meansconnected in parallel.

A further object of the invention is the provision, in apparatus of thecharacter described, of a combined actuating and indicating device andcomprised of a small neon tube with a third element built'in, adapted tofunction as a trigger tube and adapted to produce sufiicientillumination to function as an indicator.

Another object of the invention is the provision of a test stickincluding a series of high resistors terminating in a contact electrodeon one extremity thereof, having a sufficient collective resistance toreduce the current therethrough to 1 milliampere or less, and a maincircuit connected thereto including a Thyrite non-linear safetyresistor, a cold cathode tube, comprising an actuating device,extinguishing circuit means, calibrating means, sensitizing means,checking means for said extinguishing circuit means, test circuits andswitching means to render the same effective, and means to supply directcurrent thereto of the order of L10 to 150 volts, so as to have astriking voltage of not less than 80 volts.

A further object of the invention is the provision, in a device of thecharacter described, of a circuit including a cold cathode tube as anactuating device, and having it positioned to be visible to a user as anindicating dew'ce, and a transparent or translucent colored cap or thelike for preventing photo-electric effects of light upon said tube.

Another object of the invention is the provision of a potentialindicator including circuits built around a cold cathode trigger tubeand powered by means other than the circuit being tested.

Another object of the invention is the provision of a potentialindicator which employs a cold cathode gas filled tube having not lessthan three elements connected in a safety circuit between the conductorto be tested and ground potential.

A further object of the invention is the provision of a cold cathodetrigger tube in an opaque enclosure having an opening therein so thatthe cold cathode trigger tube functions additionally as an indicator,and the provision of a transparent cap or bubble which allows the tubeto be seen when it is illuminated, yet eliminating any photoelectricaction in said tube. I

A further object of the invention is the provision of a potentialoperated cold cathode gas filled thyratron type of tube in which thegrid is allowed to assume control of the tube by means of an oscillatingdirect current plate circuit in which the plate voltage is momentarilycaused to dip to the point where the plate-cathode circuit is rapidlyinterrupted and yet at the same time maintaining the gridcharacteristics of the tube.

A further object of the invention is the provision of a system of thecharacter described in which the plate cir- Patented June 13, 1961 ice 2cuit includes a relay winding whereby the relay may control remotesystems in time with actuating potentials impressed on the grid of thegas filled cold cathode thyratron tube.

A further object of the invention is the provision of a circuit of thecharacter described, in which the plate circuit has the primary of atransformer connected thereto so that the pulses of the plate circuitmay be transformed into alternating current on the secondary thereof.

Other objects and advantages of the invention will be apparent to thoseskilled in the art upon a study of this specification and theaccompanying drawings.

Referring to the drawings, which are given by way of example toillustrate the invention:

FIGURE 1 is a circuit diagram of one form of the invention;

FIGURE 2 is a circuit diagram similar to the diagram of FIGURE 1 withcertain modifications;

FIGURE 3 is a circuit diagram showing further modifications of thecircuit shown in FIGURE 1;

FIGURE 4 is a view of a test stick made according to Q the invention;

FIGURE 5 is a cross-sectional view showing a preferred arrangement ofresistors, insulators, and casing in the high tension end of the teststick;

FIGURE 6 is a view of the test stick taken along the line 6-6 of FIGURE4;

FIGURE 7 is a circuit diagram of a two unit potential indicator systemfor detecting the presence of high potentials on conductors;

FIGURE 8 is a diagram of a portion of the circuit of FIGURE 7, showingthe circuit'relation of certain of the components when a switch thereinis switched to another position;

FIGURE 9 is a diagrammatic sketch showing the use of two test sticks, incombination with a modification of the main circuit, for detecting phaseangle diiferences;

FIGURE 10 is a circuit diagram similar to the diagram of FIGURE 1 andshowing relay means for effecting controls in time with the firing ofthe thyratron tube; and

FIGURE 11 is a diagrammatic circuit showing a transformer with itsprimary interconnected with the plate circuit so that the direct currentimpulses are transformed into alternating or pulsating currents so thatthe secondary of the transformer may be connected to suitableinstrumentalities to be controlled in tune with the action in saidcircuit.

My new and improved test sticks and the circuits embodied in them havethe following important features:

(1) They are of a convenient and most useful length without beingunwieldy, andthey are comparatively light in weight and yet they aredevised to stand rough handling.

(2) The range of the circuits embodied in my sticks for averagecommercial applications, whether they are portable or fixedinstallations is from 250 volts to 50,000 volts or higher, AC. of anystandard power frequency, or DC. positive or negative; and this circuitconstitutes a complete conductive circuit extending from the conductorbeing tested to ground.

(3) Cold cathode tubes are employed in my circuits, they also functionas indicators, and photo-electric action is minimized by means of aclosure which also constitutes a light filter.

(4) The circuit includes a number of rapidly made tests to insure thesafety of the workers.

Referring now to FIGURE 1, a series of five resistors R, have oneextremity 10 constituting the tip of the stick, and the other extremity11 is connected to a circuit which forms the heart of my system, andwhich will be presently described. The values of these five resistorsdepends on the maximum voltages on the conductors to be encountered withthe test stick, at any event it is preferable that the total resistancebe of such value that low resultant currents of the order of 1milliampere or less. Between the point 11 and the ground clamp 12, isconnected a non-linear safety resistor R of the Thyrite type. A bus wire13 is connected to the point where the lower end of the resistor R isconnected to ground 12, and a second paralleling bus wire 14 has one endconnected to the junction of R and R and its other end is connected toan electrode 15 of a cold cathode gas filled tube 16.

The tube 16 has a cathode 17 which is connected via a wire 19 to the buswire 13, so that the Thyrite type resistor and the gas filled tube 16are virtually connected in parallel. The third element 18 of the tube isconnected via a branch conductor 20 to an extinguisher circuit C Rconstituting a condenser C with a resistor R in parallel therewith, andthence to the terminal 2 1 of a source of DC.

The third element 18 is also connected via a conductor 23 to a parallelcircuit R C which in turn is connected via a conductor 24 to a contact25 on a double pole double throw test switch SW2. A condenser C isconnected between one end of a resistor R and the bus wire 13, and theother end of the resistor R is connected via a wire 33 to onemid-terminal 32 of the switch SW2. The resistor R is a current limitingresistor, and the condenser C together with R is a test circuit.

A resistor R termed a calibrating resistor, has one end connected to thebus wire 14, and the other end is connected via a wire 34 to the contact26 on switch SW2. The resistor R also has said last end connected, via awire 35, to a series of test resistors R-, which are, in turn, connectedto contact 31 on SW2.

A resistor R termed a sensitizing resistor, has one end connected to thebus wire 14 and its other end is connected to a contact 36 on switchSW1. Contact 38 is connected via a wire 37 to the bus wire 13 and to acontact 27 on SW2. A condenser C connected in parallel with the bus wire13 and wire 14 functions as an A.C.-D.C. equalizer. In some instances, Iwish to include a relay winding serially between the point 2-1 and thepoint where the condenser C and resistor R are connected to the wire 20afor controlling other instrumentalities in time with the firing of thetube 16.

FIGURE 2 shows a circuit which is substantially identical with thatshown in FIGURE 1, except for a modifi: cation. All circuit componentsin FIGURE 2 having the same numerals as those in FIGURE 1 are identicalwith those already described in connection with FIGURE and the followingdifferent components are: The wire 23 leading from the control element18 in the tube 16, has a branch wire 41 connected thereto, and this wireleads to a neon tube 40, which is, in turn connected to the terminal 21via a wire 42, an extinguisher circuit C R and via a wire 43 to theterminal 21. In using the circuit of FIGURE 2, the steps are the same asfor FIGURE 1, except that the neon tube, may be used for an indicatorinstead of using the trigger tube 16 for the purpose.

The circuit shown in FIGURE 3 is substantially the same as that shown inFIGURE 1 except that in, place of the series of resistors R I employ aplurality of capacitors C connected in series. One end of the series isconnected at the point 11 and the other end is connected to the tipelectrode 10. The capacitors C comprise a sufficient number havingvalues to limit the firing load to a maximum of one mill as a safetyfactor for the person holding the stick, for instance, as was the caseabove in connection with FIGURE 1. Since the other elements of thecircuit are the same as in FIGURE 1, it is believed to be unnecessary todescribe them again in connection with FIGURE 3 especially since thenumerals on the various elements of the circuit are the same as those inFIGURE 1.

The elements of the circuits shown in FIGURES l,

4 2 and 3, and any variations thereof may be built into a test sticksuch as that shown in FIGURE 4. The test stick shown in FIGURE 4 is acompletely self contained and portable unit which may be used anywhere.

Before describing the entire test stick, reference is made to FIG. 5which shows a portion of the high tension end of the test stick and onepreferred embodiment of a novel method of mounting the resistors formingthe series R of FIG. 1 or 2. In cases where capacitors such as C areused, the method of mounting them and connecting them to the electrodetip 10 is similar to the method of mounting the resistors which will nowbe described.

The electrode 10 is mounted in an insulator 45 which has a tubular shank46 and a tapered apex 47, the taper being such as to form a shoulder 48adjacent to the shank 46. A tubular insulator '50 has an interior wall49. Forming a fit within the wall 49 is a tubular insulator 51 which hasa tubular wall 52 and a perforated head 53 forming a closure-for one endthereof. The other end has a portion 54 of reduced diameter, the purposeof which will be presently described.

The interior bore 55 of the insulator 51 forms a socket into which oneend of a resistor 56 may be positioned. Adjacent to the head 53, acupped metallic spring washer 57 is positioned and this may be made ofany suitable material such for example, as bronze. A screw 58 has ashank 59 extending through the perforate head 53 and is screwed into oneend of a helical spring 60 and the electrode 10 may have a correspondingthreaded portion 62 to be screwed into the other end of the springthereby forming a resilient connection between the washer 57 and theelectrode 10. The second insulator is generally H-shaped in crosssection and carries opposed sockets 63 and 64 for the reception of theends of resistors such as the resistor 56. At the bo tom of the socket63 is a spring washer 57 and likewise at the bottom of the socket 64 isa second spring washer 57 and these are mechanically connected by ametallic screw 66 passing through a central hole in a wall 67 definingthe bottoms of said sockets.

The screw 66 passing through both spring Washers 57 engages a nut 61making electrical contact between the spring washers 57. The insulator65 has a portion 68 of reduced diameter at one end thereof and a portion69 of reduced diameter at the other end thereof. The diameters of theportions 68 and 69 are also of the portion 64 being substantially thesame.

The resistor 56 is positioned in one end of one of the sockets of aneighboring insulator so that it is in contact with the spring washerstherein and is wholly supported by said sockets. Since several resistorsare employed in my new and improved test stick, the ends of the otherinsulators are mounted in sockets in insulators identical with theinsulator 65, it is not believed necessary to describe each and everyone over again. However, the last one in the series, namely, theinsulator 70 is cylindrical in form and it has a socket 71 formed in oneend thereof which faces the nearest insulator 65 and cooperates with thelatter to support the last resistor 56 in the series. A spring washer 57is positioned in the bottom of the socket 71 and a screw 72 similar tothe screw 58 extends through a central passage 73 formed therein and isconnected to said last spring washer. This conductor connects to the buswire 14 shown in FIG. 1 or 2. The insulator 70 is substantiallyidentical with the insulator 51 and has a portion 74 of reduced diametersimilar to the portion 54 surrounding the socket 71 and its diameter ispreferably substantially the same as that of portions 54, 68 and 69. Atubular insulating sleeve 75 forms a working fit on the portion 54 and68, for example, as it is preferably slightly shorter than the distancebetween the shoulders adjacent to said portions of reduced diameters,when the resistor 56 is positioned in the sockets 55 and 63.

Returning now to FIGURE 4, the test stick has a high tension portionformed of insulators and resistors gssavos such as described above andthis portion may be socketed into a boss 76 having a flange 77. Spacedapart from the flange 77 is a second flange 78 which forms the base fora compartment 79 containing the elements shown in the circuit ofFIGURE 1. Between the flanges 77 and 78 is a spacer member 81, andpassing through this spacer is a conduit 82 through which the bus wire14 extends into the compartment 79. The components are all enclosedwithin this compartment with the exception of the cold cathode triggertube 16, which extends through the casing of the compartment 79 so as tobe visible to a user. In order to prevent or minimize photoelectricaction in the tube 16, it is covered with a dome 83 of transparent ortranslucent material and of a color to filter out rays of light whichwould tend to cause photoelectric action within the tube.

Joining the compartment 79 is a tubular member 84 which forms the mainhandle of the test stick and which may contain a battery, for example,150 volts to furnish the necessary potentials to test and operate thestick. The inner end of the battery is connected to the terminal 21 andthe outer end of the battery is connected to the negative side 22 of thecircuit. The handle member 84 has a closure disk 85 and it supports aspring 86 which maintains the battery in contact with the points 21 and22 at all times. A cable 87 is connected to the ground, which is thenegative bus wire 13 and it terminates in a ground clamp or clip 12.

Use of test stick In order to determine the presence of potentials onconductors, the following steps are taken, the circuit of FIGURE 2,having a battery of 135-150 volts connected to the terminals 21 and 22:

(1) Connect the ground clamp or clip 12 to ground.

(2) Throw switch SW2 to the test position, thereby connecting the point32 to the point 31, by means of the blade 29, and at the same timeconnecting the point 27 to the point 25 by means of the blade 28. Whenthis is done, the visual indicator 16 should pulsate. If it does, thetip should then be touched to ground and the indicator should go out dueto the fact that when this is done the voltage or potential is therebyreduced to a value too low to trigger the indicator. When the tip 10 isremoved from ground, the indicator should light up again, due to thefact the test circuit is changed to the extent that the potential acrossthe indicator and actuator tube is sufficient to again fire it.

(3) Throw the test switch SW2 to the normal position where the blade 29connects contacts 32 and 30 together and the blade 28 connects contacts27 and 26 together. Then touch the tip 10 to the conductor to be tested,and if the indicator 16 lights, the conductor is alive.

(4) Step #2 is repeated in its entirety to double check the stickcircuit, and if it checks all right it is believed safe to assume thatthe indications obtained in Step 3 are reliable.

In the form of the invention shown in FIGURES 7 and 8, two units areshown, one designated as 88 may comprise the test stick per se with'itscold cathode combined actuator and indicator and a second unit 90 whichis arranged to be connected or disconnected from the test stick unit 88,the connection being made via a 2-wire shielded cable 89. The power unitis connected to a suitable source of current by means of a wire 91 and aground wire 92. Suitable sources of power are as follows:

Alternating current 60 cycles, 110 to 135 volts Alternating current 25cycles, 110 to 135 volts Direct current with a positive live leg and thenegative leg grounded Dry (B) batteries such as are described aboveherein in connection with FIGURES 1 to 4.

The stick unit 88, FIGS. 7 and 8, includes a series of high resistors, Rwhich has one end connected to an electrode 10, and the other end isconnected to a non- 6 linear resistor R and to a conductor 93 which iscom nected to the control element or grid 94 in the cold cathode tube16. The other end of the non-linear resistor is connected to a conductor95 which is in turn connected to the cathode 97 and to the ground wire96.

Bridged across the conductors 93 and 96 is a calibrat-' ing resistor Rand this is bridged by a condenser 0., which functions as an equalizerfor alternating currents. The anode 15 of the tube '16 is connected to aresistor R which is bridged by a condenser C (constituting anextinguishing circuit), and resistor R is in turn connected via a wire98 to the positive terminal 99 of the power supply and this in turn isadapted to be connected to a suitable source of current as willpresently be described.

Bridged across the conductors 93 and 95 is a resistor R which in somerespects is similar to the resistor R described above for controllingthe sensitivity of the circuit. In series with the resistor 3 is aswitch SW3 for throwing the resistor R into and out of the circuit. Theconductor 96 carries a detachable coupling 100 and like wise the shield95 has a terminal 101.

The above described elements comprising the test stick per se may beconnected to any suitable source of current, as was pointed out aboveand in the first example B batteries of 150 volts have their negativeterminal 102 connected to a conductor 103 and the positive terminal 104is connected through a switch 105 to a bus wire 106. When the switch 105is closed, current is supplied to the conductor 106 via the choke 107which is positioned between filter condensers 108 and 109. A volt meter110 has one terminal connected to a bus wire 111 which is in effect anextension of the wire 106 (through the choke 107), and the other side isconnected to the bus wire 103 whenever a switch 112 is closed. The wire111 is connected to the terminal 99 and the wire 103 is connected to theterminal 101 as is the ground wire 113 and this ground wire is connectedto the ground wire 96 through the terminal 100.

Where 60 cycle alternating current is used as the source of current, thewires 91 and 92 are connected to it, so that current coming over thewire 91 passes through a rectifier 114 and thence it passes through thefilter system comprised of the filter condenser 108, the choke 107 andthe filter condenser 109 and from the filter system the rectifiedcurrent is delivered by the terminal 99 to the anode of the cold cathodetube 16. A four-pole double throw switch 115 has a blade 116 whichcooperates with contacts 117 and 118; a blade 119 which cooperates withcontacts 120 and 121. It also has a blade 122 which cooperates withcontacts 123 and 124 and a blade 125 which cooperates with contacts 126and 127. A condenser 128 is connected between the switch blades 116 and122 and a pair of condensers 129 and 130 is connected in series witheach other and to the switch blades 119 and 125. A mid-tap 131 isconnected through a limiting resistor 132 to a test plate 133. The buswire 111 is connected via a wire 134 to the switch contacts 117 and 123,and the switch contact 127 is connected via a wire 135 to the bus wire103 which is the negative side of the source and which is also ground.

The purpose of the above arrangement is to provide potentials greaterthan the supply voltage for the purpose of testing the test sticks. Forexample, if the source of current connected across 91 and 92, is, forexample, 110 volts and 60 cycles, it is by the time it is rectified andreaches the volt meter, in the neighborhood of 100 volts. Now, with theswitch in the position shown in FIG. 7, the condenser 128 is connectedacross the approximately 100 volt filtered potential.

The series condensers 129 and 130 are also connected across thispotential and they are likewise charged up to 100 volts. Now, when theswitch 115 is thrown to the position shown in FIG. 8, the condenser 128is connected in series with series condensers 129 and 130 so that themid-tap 131 impresses upon the test plate 133 approximately 50 volts ofpotential from the condenser 130 plus 100 volts from the condenser 128,making a total of 150 volts to be added to the 100 volt supply to,obtain 250 Volts. Obviously, by the same method, I can, by increasingthe number of poles in the switch and utilizing more condensers, provideany desired potential from the comparatively low voltage source.

The test plate 133 is preferably not directly connected to the conductor131 instead I find it very convenient to yieldingly mount the test plateon its support so that when the tip of the test stick is touched to it(with the light pressure) the test plate is moved into contact with theconductor 131.

Referring now to FIGURE 9, a further modification is shown for detectingphase angle differences.

In alternating current distribution and transmission systems where poweris supplied over many parallel paths, it is necessary, when parallelingcircuits, that each have the same phase angle. The potential indicatingdevice may be modified and utilized for the purpose of determining thatit is safe to close switches, or circuit breakers in such circuits. Thesensitivity control 150 may be adjusted so as to give indicationswhenever the phase angle exceeds a predetermined value.

The phasing may be done directly on high voltage equipment without thenecessity of utilizing potential transformers and otherinstrumentalities heretofore employed.

In FIGURE 9, conductors 137 and 138 may be of different phases or theymay be of the same phase but it is assumed that the phase relations areunknown. If 137 were phase A and the phase of 138 were unknown, thedevice would be used to determine whether or not the two were in phase;a switch 139 may be positioned between them to be closed when it is safeto do so. A modified double test stick has corresponding tips 10 and 10awhich form the extremities of resistors R and RR respectively. These mayeach be comprised of a series of resistors (for example, resistors)similar to those described in connection with FIGURE 1 above. In themodification, the non-linear resistor R has one end connected to thelower extremity of R which is designated by the numeral 14 and has itsother end connected at 141 to the lower extremity of the resistor RR Abus wire 142 is connected to the point 140, and a second bus wire 143 isconnected to the point 141. The bus 142 is connected via a branch wire144 to an electrode 15 of a cold cathode gas filled tube 16. The tube 16has a cathode 17 which is connected via a branch wire 145 to the buswire 143. Thus, the tube 16 is actually connected in parallel with thenon-linear resistor R The third element 18 of the tube 16 is connectedthrough an extinguisher circuit C R constituting a condenser C with aresistor R in parallel therewith and thence to the plus terminal 146 upa battery 148, which is substantially the same as either of thosedescribed herein above. Between the tube 16 and the non-linear resistorR I provide a phase angle sensitivity control 150 which is connected inparallel with the resistor R and the tube 16. The negative terminal 147of the battery 148 is connected via a wire 151 to the bus wire 142 thuscompleting the circuit of the phase angle detector.

Use of the device for detecting phase angle differences It is pointedout above that the conductor 137 was connected to a known phase, forexample, phase A and that the conductor 138" was connected to an unknownphase which might be A or B; Now, with the stick positioned so that theelectrode is in contact with the conductor "137 and with the electrode10a in contact with the conductor 138, the phase relation can bedetermined.

If the trigger tube 16. lights up thisindicates. that the two.conductorsare not in phase with each other and thereforethe switch. should not beclosed. If; on the other hand, the tube 16remainsdark, the; switch maybe, safely c osed. ca s h t c nduc o s ar n n se. Of

course, the device should be tested beforehand, and one method oftesting it would be to individually test the branch with the electrode10 on it in a manner similar to that described herein in connection withthat in FIGURE 1 and then portion carrying the electrode 10a can betested in the same manner as described above herein to make sure theboth branches of the device are operable.

Further modification of the device of FIGURE 9 contemplates theprovision in place of the sensitivity control (which may be a variableresistor). I provide at least two such resistors in series each beingindividually adjustable so that by means of one of them, I can (1)pre-set the device to a desired operating voltage being tested and (2) Ican pre-set for a desired phase angle so that the lighting of thetrigger tube would indicate a phase difference in excess of the desiredphase angle.

Referring to FIGURE 10, I show a circuit winding 152 connected in serieswith the conductor 20, between the combined capacitor resistor C R andthe positive terminal 21 of the Source of current. The relay hasswitching contacts 153, 154 which control a device 155 remote from therelay by connecting it to a source of current such as the source 156.

FIGURE 11, a further modification is ShOWn wherein the primary winding157 of a transformer 158 is connected between the capacitive resistancenetwork C R and the plus terminal of the direct current source ofcurrent 21. The transformer 158 also has a secondary winding 159 whichis connected in a circuit with a device adapted to utilize alternatingcurrent for example a lamp 160. In both of the modifications (FIGURE 10and FIGURE 11), the remote control is effected in definite time relationto the firing of the tube.

Although I have herein described two systems for indicating the presenceof potential on electrical conductors and some modifications thereof, itwill be understood that these are given by way of example to illustratethe invention and how to practice it and is not intended to belimitative, as many changes may be made in the arrangements shown anddescribed within the scope of the following claims.

I claim:

1. In a device for indicating the presence of potentials on electricalconductors, a circuit having current limiting means therein for limitingthe current passing through said device to a predetermined value, a gasfilled tube in said device adapted to function both as an actuator andas an alarm indicator and having at least an anode, a cathode, and acontrol element, a connection between said control element and one endof said current limiting means, a second connection between said cathodeand ground, non-linear resistance means connected in parallel with theconnections to said control element and cathode, an extinguisher circuitconnected between said anode and one side of a source of currentindependent of any potential present on said conductors, anddesensitivity control means connected in parallel with said resistancemeans and having a switch serially included in said connection, theother side of said source being connected to ground, therebyconstituting means to supply a firing potential to said tube.

2. In a device for indicating the presence of potentials on electricalconductors, a circuit having current limiting means therein; a coldcathode gas filled thyratron tube in said device having at least ananode, a cathode, and a control element; a connection between saidcontrol element and one end of said limiting means, a second connectionbetween said cathode and ground, non-linear resistance means connectedin parallel with said control element and cathode, an extinguishercircuit connected between said anode and a first side of a source ofcurrent independent of any potentials present on said electricalconductors, and including a resistance-capacitor combination adapted-t0produce the effect of momentary reducing theplate potential. to allowthe grid to reassume control of. the, cir uit without appreciablychanging the characteristics of said tube, and a connection between theother side of said source and ground, forming with said first connectionto said source, means to supply a firing potential to said tube.

3. In a device for indicating the presence of potentials on electricalconductors, a circuit having current limiting means therein, non-linearresistance means connected between one end of said current limitingmeans and ground; a gas filled tube in said device having at least ananode, a cathode, and a control element, said control element andcathode being connected in parallel with said nonlinear resistancemeans; an extinguisher circuit connected between said anode and oneterminal of a source of current, the other side of said source beingconnected to ground, test circuit means interconnected with the elementsof said tube and including switching means which normally connects saidcalibrating resistor in parallel with said non-linear resistor, saidcalibrating resistor comprising means for equalizing said circuit so asto make it equally effective on both alternating and direct current;said switching means when in a test position, being adapted to checksaid extinguisher circuit and to impress a test circuit; which includesa capacitor and resistance means, in series with said calibratingresistor for determining whether said device is in operative condition.

4. In a portable test stick for indicating the presence of electricalenergy on conductors, a circuit having current limiting means therein, agas filled tube in said device having at least an anode, a cathode, anda control element, said control element and cathode being connected inparallel with non-linear resistance means connected to said limitingmeans and ground respectively, a battery having its positive terminalconnected to said anode via an extinguisher circuit, and a negativeterminal being connected to ground, a calibrating resistor in parallelwith said non-linear resistor, test circuit means interconnected withthe elements of said tube and including double pole double throwswitching means which normally connected said calibrating resistor inparallel with said non-linear resistor, said switching means when in atest position being adapted to check said extinguisher circuit and toimpress a test circuit, which includes a capacitor and resistance means,in series with said calibrating resistor for firing said tube if saiddevice is in operative condition.

5. In a portable test stick for indicating the presence of potentials onelectrical conductors, comprising a tubular portion of one diameter, asecond tubular portion larger in diameter than said first portion, and ahousing intermediate said portions, current limiting means in said firstportion having one end terminating in a tip electrode, a battery in saidsecond portion and having means for connecting the negative terminalthereof to ground, a nonlinear resistor connected between the otherterminal of said current limiting means and ground; a gas filled tubethrow switching means which normally connects a calibrating resistor inparallel with said non-linear resistor; said switching means beingadapted to be thrown to a test position to check said extinguishercircuit and being adapted to impress a test circuit, which includes acapacitor and resistor means, in series with said calibrating resistorfor determining whether said device is in operative condition or not.

6. In a device of the character described, an input circuit havingcurrent limiting means therein for limiting the value of currenttherethrough; a gas filled cold cathode tube having an anode, a cathodeand a control grid; said grid and cathode being connected to saidcurrent limiting means and to ground, respectively, non-linearresistance means connected in parallel with said last connections, anextinguisher circuit connected between said anode and one side of asource of direct current, a connection between the other side of saidsource and ground, said extinguishing circuit comprising a combinationof a resistor and a condenser in parallel, said control element beingadapted to control the firing of said tube, whereby the charging currentof the condenser causes the anode circuit to fire after the grid circuithas been fired and then extinguished by the rapid discharge of saidcondenser via the resistor connected in parallel therewith and effectingintermittent operation of said circuit during which the grid reassumescontrol without materially changing the characteristics of the gridcircuit or the grid-anode transfer voltage and current.

7. A device according to claim 6 in which the connection from the otherside of the said source of current extends to the cathode of said tubeand in which each of said current limiting means constitutes an array ofresistors of such values as to limit the possible current flow to apredetermined quantity.

References Cited in the file of this patent UNITED STATES PATENTS1,744,840 Streiby et a1. Jan. 28, 1930 1,795,176 Lloyd Mar. 3, 19311,906,644 Sleeper May 2, 1933 2,093,854 Swart Sept. 21, 1937 2,284,423Hansell May 26, 1942 2,482,016 McCoy Sept. 13, 1949 2,632,785 Knopp etal. Mar. 24, 1953 2,637,786 Bordevieck May 5, 1953 2,648,817 SchiedelAug. 11, 1953

